The present disclosure relates generally to electronic devices and, more particularly, to reducing display artifacts, such as flicker, in displays of the electronic devices.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Liquid crystal displays (LCDs) are commonly used as screens or displays for a wide variety of electronic devices, including consumer electronics such as televisions, computers, and handheld devices (e.g., cellular telephones, audio and video players, gaming systems, and so forth). Such devices typically provide a flat display in a relatively thin package that is suitable for use in a variety of electronic goods.
LCD panels include a backlight and an array of pixels. The pixels contain liquid crystal material that can modulate the amount of light that passes from the backlight through the pixels. By causing different pixels to emit different amounts of light, the pixels may collectively display images on the display. Modulating the amount of light that passes through each pixel involves controlling electric fields applied to the liquid crystal material of each pixel. In particular, each pixel may have a pixel electrode that stores a data voltage. Groups of pixels may share a common electrode that provides a common voltage (VCOM) voltage. The voltage difference between the data voltage on the pixel electrode and the common voltage on the common electrode creates an electric field in each pixel. The electric field causes the liquid crystal material to modulate the amount of light. Indeed, the liquid crystal molecules in the liquid crystal material rotate in a way that causes a particular amount of light to pass through the pixel; this rotation depends on the magnitude of the electric field. That is, what matters is the magnitude of the voltage difference—in fact, a positive voltage difference or a negative voltage difference of the same magnitude will generally cause the liquid crystal material to emit the same amount of light through the pixel. Thus, controlling the magnitude of the voltage difference between the pixel electrode and the common electrode controls the amount of light that passes through each pixel.
Yet the common voltage could differ from an expected voltage level under certain conditions. For example, the act of programming the pixels could cause a voltage known as a “kickback” voltage to change the common voltage from what would otherwise be expected. If the common voltage is different than expected, the voltage difference between the data voltage supplied to the pixel electrode and the common voltage on the common electrode could be different than expected. This could cause pixels to emit an incorrect amount of light and therefore produce a less desirable image. Moreover, to prevent long-term image artifacts, the polarity of the voltage difference may be selected to alternate from time to time, while keeping the same magnitude (e.g., if the common voltage is 0 V, and the desired magnitude of the voltage difference between the data voltage and the common voltage is 1 V, the data voltage may be supplied as 1 V at one time and −1 V at another time). But when the common voltage is different than expected, changing the polarity by changing the data voltage will produce different magnitudes of voltage differences at different times—and therefore cause different amounts of light to be emitted by the pixels at different times, even when the pixels should be emitting the same amount of light. When the magnitudes cause enough differences in the light to become visible to the human eye, this may appear as flickering artifacts on the display.